Many U.S. health care providers are still not comfortable prescribing buprenorphine to treat opioid addiction, according to a new study.

While the federal government recently took steps to deregulate buprenorphine prescribing, it did not lead to a significant increase in overall prescribing volume, STAT reports.

Prescribers previously needed to undergo special training to obtain an “X-waiver,” a special license needed to prescribe buprenorphine. The license required eight hours of additional training for physicians and 24 hours for physician assistants and nurse practitioners. Congress recently eliminated the training requirement, but prescribers certified by the Drug Enforcement Administration (DEA) must undergo education to maintain their license.

The new study found clinicians list many reasons they don’t prescribe buprenorphine. These include concerns about DEA overreach, insurance approval processes, lack of institutional support, concerns about buprenorphine diversion and concerns about treating patients with opioid use disorder. In addition, many physician assistant and nurse practitioner prescribers said they could not find a supervising physician to oversee their practice, which several states still require.